DOUBT

Dear Nandiniraj,

Please cc r-help in your emails so that others can see what happened 
with your problem.

You don't provide enough information to know what exactly is the source 
of your problem  -- you're more likely to get effective help if you 
provide a minimal reproducible example of the problem -- but it's a good 
guess that the variable (HHsize or perhaps some other variable) isn't in 
the newdata data frame.

Best,
  John